[file: KANOwaterLDDrevisedJune03]

Water, land and health in urban and peri-urban food production: 
the case of Kano, Nigeria

J.A. (Tony) Binns, R.A. Maconachie and A. I. Tanko

Dr J A (Tony) Binns, Reader in Geography, School of African and Asian Studies, University of Sussex, Falmer, Brighton, BN1 9SJ, UK

R A Maconachie, Graduate Researcher, Centre for the Comparative Study of Culture, Development and Environment, University of Sussex, Falmer, Brighton, BN1 9SJ, UK

Dr A I Tanko, Senior Lecturer, Department of Geography, Bayero University, Kano, Nigeria

Correspondence to: J A (Tony) Binns, School of African and Asian Studies, University of Sussex, Falmer, Brighton, BN1 9SJ, UK. E-mail: j.a.binns@sussex.ac.uk

Water, land and health in urban and peri-urban food production:
 the case of Kano, Nigeria

Abstract
In sub-Saharan Africa, urban and peri-urban food production has been identified as an important resource for meeting the challenges of rapidly growing cities, and the positive aspects of such production have been well documented in the literature.  This paper examines some of the health and environmental concerns associated with urban and peri-urban agriculture (UPA). Empirical evidence from the city of Kano in northern Nigeria suggests that there is currently much reason for concern as industrial and domestic toxins are reaching dangerously high levels. As soils and water channels become increasingly polluted, the sustainability of urban and peri-urban food production is questioned. Since the health implications of long-term exposure to toxins are unclear, it is suggested that coordinated longitudinal research involving urban planners, agricultural scientists and health specialists is urgently needed.  In addition, it remains crucial that government and institutional actors effectively monitor and enforce both environmental and zoning bi-laws, if the health and environmental constraints of UPA are to be overcome, and the future sustainability of production is to be assured. 

Key words: Health, environment, urban, peri-urban, food production, Kano, Nigeria

Introduction
Since the 1960s, a dramatic acceleration in rapid urban growth, combined with surging levels of grinding poverty, have heightened concern for the 'urban crisis' that has unfolded in sub-Saharan Africa.  Although the majority of the sub-Saharan population still live and work in rural areas, the average annual urban growth rate of 4.8 percent between 1980 and 1993 was more rapid than in any other part of the world and is cause for great alarm (World Bank, 1995a).  In the last ten years, urban populations have continued to escalate, and it is likely that half of Africa’s people will soon be living in cities (HABITAT, 1996).  In Nigeria, Africa’s most populous country, there are more cities with over a million people than any other nation on the continent, and as rural areas surrounding growing cities continue to be integrated into the urban system, Nigeria will need to incorporate these urbanisation trends into its future development strategy. While there is no disputing that African cities have undergone rapid growth in the past four decades, there is much debate over the causes and effects of the urban transformation, and the ensuing social and ecological deterioration of the urban landscape. As sub-Saharan cities continue to expand and leave their 'ecological footprints' (Rees, 1992) on their surrounding environments, urban fringes are being rapidly transformed with the intensifying competition for scarce resources, frequently resulting in the progressive degradation of the peri-urban environment. Although there appears to be a lack of consensus on the best way to ameliorate many of the desperate conditions that have ensued in and around African cities, in recent years a great deal of attention has been given to what the Brundtland Commission referred to as the great 'urban challenge' (World Commission on Environment and Development, 1987). As a result, there is now a vast literature that addresses many of the issues confronting the sustainability of urban and peri-urban livelihoods (for example, see Lynch et al., 2001; Briggs and Mwamfupe, 2000; Tacoli, 1998; Aldington, 1997).   In particular, the role that urban and peri-urban agriculture (UPA) can play in improving livelihoods has been well documented, and many researchers have suggested that such intensive cultivation may indeed be the panacea for the urban food supply deficit associated with many burgeoning Third World cities (Binns and Lynch, 1998).

Overwhelmingly, the work published on UPA has highlighted the positive aspects of such activities.  Previous studies have pointed out that UPA increases urban food security (Atkinson, 1995), serves as an important coping mechanism in the informal economy (Lourenço-Lindell, 1995; Gefu, 1992), is an important income-generating activity (Freidberg, 1996), may help in reducing urban malnutrition (Egziabher et al, 1994; von Braun et al 1993), and can even play a role in the advancement of women in African cities (Freeman, 1993). On the other hand, and to a lesser extent, there has also been academic interest in exploring some of the negative consequences associated with UPA.  For example, Mvena et al. (1991) conclude that water shortages, the threat of waste contamination, and conflicting land use activities can make the promotion of urban farming difficult in many situations. It was perhaps not until 1992, at the UNCED Earth Summit in Rio, that the environmental debate was finally broadened to focus international attention on the so-called 'brown agenda', dealing with pollution problems, environmental hazards and poverty.  In particular, since peri-urban zones serve as both resource extraction sites and depositories for urban waste, there has been a growing interest in the sustainability of expanding crop, livestock and natural resource production in these areas. As land pressures and the competition for key resources have mounted in peri-urban localities, an increasing incidence of land degradation has been identified as a significant environmental problem. Whilst there is much variability in both the level and nature of understanding land degradation, a concept which is socially constructed, it is apparent that there are some shared concerns regarding the current state of many peri-urban environments. As Stocking and Murnaghan (2001) suggest, land degradation may be best regarded as an ‘umbrella’ term, used to convey the numerous ways in which the quality and productivity of land may diminish from the perspectives of different land users. With respect to UPA and non-food resource production, an understanding of the interlinkage between the various manifestations of degradation remains crucial if the future sustainability of urban and peri-urban livelihoods is to be assured.

If UPA is to be encouraged and fully incorporated into urban planning strategies, then there is a pressing need for further research.  As Lynch et al (2001: 170) point out, perhaps one of the main problems with much research has been that it, '…identifies the advantages of urban agriculture from a relatively restricted perspective', and fails to engage with, '…a greater understanding of urban agriculture in relation to specific issues such as land tenure, health and environmental concerns.'  In this light, this paper considers some of the health and environmental concerns associated with UPA.  Empirical evidence presented from the city of Kano in northern Nigeria suggests that there are many areas where joint research between urban planners, agricultural scientists and health specialists must be carried out in the immediate future.

Health and environment in the peri-urban zone 
The peri-urban zone can broadly be defined as an interface where there has been a blurring of the rural and urban, and is characterised by mixed land use by a wide range of stakeholders.  However, any researcher who has undertaken fieldwork in sub-Saharan Africa, will be well aware of the difficulties presented in trying to delimit and define the so-called 'urban', 'peri-urban' and 'rural' zones.  Indeed, it seems that the countryside that immediately surrounds urban areas, or the 'peri-urban' zone, does not have a simple definition that is universally accepted by all scholars.  Although the term 'peri-urban' is usually used to convey the overlapping of rural and urban areas, Bryant et al. (1982) point out that the definitional problem lies mainly in the difficulty of delimiting the spatial extent of this dynamic region, and in the interpretation of the notion of transition.  An extended exploration of the numerous interpretations of 'peri-urban' is certainly beyond the scope of this paper, and will be left for further debate elsewhere.  However, for present purposes, the region is perhaps best thought of as a transitional environment of mixed land-uses between a city's continuously built-up area and its rural hinterland where, '…economic and social activities are directly affected (beneficially, as well as to their detriment) by the presence and expansion of the city' (Mwamfupe, 1994:12).  

Food production requires access to land, water and fertilizer, all of which are scarce in supply in a peri-urban environment, and as a result, out of desperation, waste bi-products and contaminated water are often used as inputs.  An in-depth review of peri-urban natural resource-linked health issues carried out by Birley and Lock (1997) highlights the numerous ways that peri-urban surface water is polluted (also see Birley and Lock 1998). For example, domestic contamination from people washing, bathing, defecating and urinating is commonplace, and inadequate sewerage facilities or the presence of landfill sites further complicates the problem.  Agricultural chemicals and industrial effluent frequently pollute groundwater and soils, and since major roadways often traverse peri-urban areas, heavy metals associated with traffic pollution may also cause further contamination of crops (see Mage and Zali, 1992 or Alloway 1995 for further discussion). While studies in Nigeria have revealed high levels of lead in the dust from unpaved roads (Birley and Lock, 1998), other research examining dry season Harmattan dust deposition in Kano has found traces of lead in samples, which is also probably due to automobile exhaust emissions (Wilke, et al., 1984).

Of particular threat to fadama, or lowland, irrigation crops in dryland peri-urban areas are industrial effluents from factories and manufacturing facilities which contaminate irrigation channels. In the case of Kano, there is an immediate environmental threat posed by the presence of a large number of tanneries which discharge substantial quantities of chromium salts and numerous other toxins into water sources (Birley and Lock, 1998).  In addition to the health hazards associated with contaminated peri-urban water sources, there has also been a great deal of concern that stagnant water channels may increase the abundance of mosquito breeding sites and hence the risk of malaria and other vector-borne diseases (Lindsay et al., 1990; Trape et al., 1992; Trape and Zoulani, 1987).

The increased use of urban solid waste as fertilizer may cause additional health hazards.  In Kano, the long established interaction between the city and its hinterland has been well documented by writers such as Mortimore (1975), who provides a detailed account of the donkey-load exchange involving manure and urban waste taken out of the old city and fuelwood brought into the city from the rural areas.  The transfer of urban waste products to the hinterland still exists today, but on a much larger scale where lorries now mainly transport the refuse rather than donkeys.  However, it is possible to claim that this much-documented symbiotic relationship is currently under stress from a variety of new pressures that have been introduced into the system.  Sustainable methods of waste disposal presently prove to be more challenging, but many farmers do continue to recycle waste products and use them on their plots.  Although, composting organic wastes has positive effects in improving the fertility of the soil, and may destroy pathogens if composting temperatures are high enough, there is also evidence to suggest that there is a danger of introducing heavy metals into the food cycle if composting is carried out improperly (Birley and Lock, 1998).  Both sludge from factories and untreated raw sewage from toilets are often applied directly onto peri-urban farm plots, and can carry viruses and high levels of faecal coliforms.  In the case of Kano, farmers often apply solid waste from tanneries, which not only emits miasmal odours, but is an excellent breeding ground for disease vectors. The use of unsorted urban waste as fertilizer has also caused polythene bags to accumulate on many farm plots, and this has now become a major environmental hazard throughout Nigeria, and indeed in many other African countries.

UPA and health in Kano
Kano, the largest city in northern Nigeria, has an estimated population of between 2 and 3 million, and serves as an important market for resources produced in the peri-urban zone.  Based on data collected in three field surveys undertaken in 1996, 1998, and 2000 (see Binns and Fereday, 1996; Binns and Lynch, 1998; Olofin et al, 1997), previous research on the significance of urban agriculture in Kano has concluded that urban farms make very significant contributions to city nutrition, household food security, employment and environment. Although there does not presently appear to be official recognition of UPA in Kano, city farming is widespread and is tolerated as an important response to the economic and social conditions faced by many poor individuals. As Lynch et al (2001) suggest, the promotion of an ‘enabling environment’ in which UPA is encouraged and supported remains crucial, especially in terms of how agricultural activities fit in with urban structure, urban problems and the lifestyles and livelihoods of individual actors in the peri-urban interface. Above all, two key factors – security of tenure and the use of heavily polluted water – have been identified as major constraints in the further development of urban farming in Kano (Lynch et al., 2001).

There appears to be much cause for concern with respect to pollution and health issues associated with UPA in Kano.  The city is located in a semi-arid zone, with an average annual rainfall between 1961 and 1991 of under 700mm (Lynch et al, 2001).  Dry season agriculture is only possible in low-lying fadama depressions where the water table is close to the surface, and there is intense competition for peri-urban plots where such irrigated cultivation is possible.  The combination of Kano's low and unreliable rainfall, its burgeoning population, and industrial pollution from abattoirs, tanneries and factories seriously threatens the quantity and quality of local water resources. Further compounding the problem is the inadequate sewerage provision leading to the discharge of effluents into rivers and drains.  As Lewcock (1995) warns, contamination of water sources is a major threat, especially in the absence of adequate rainfall, which might serve to dilute and flush out toxic elements. To mention but one example, the decomposition of refuse from the food industry has been reported to have contaminated virtually all of the boreholes in Kano's Bompai industrial estate in the eastern part of the city (Egboka et al.,1989:61).  

Although there are many health issues associated with UPA in Kano, the incidence of wastewater discharge is possibly the biggest threat to city farming, and has been identified as a major environmental hazard in the region (Tanko, 2002; Bichi, 2000).  Located within the city's three industrial estates – Bompai, Challawa and Sharada – a large number of rubber, plastics, food, metallurgical and manufacturing industries generate highly polluted effluents which are discharged, in an untreated form, into adjacent water courses. According to the Ministry of Commerce and Industry, within these estates which encircle the city and utilise its limited water resources, there are 43 food processing industries, 63 aluminium, metal and wood factories, 50 plastic rubber and tyre factories, and over 32 chemical and cosmetic industries (cited in Bichi, 2000:306).  

However, it is perhaps the tannery and textile industries, using the largest quantities of water and producing the greatest amounts of waste water, that constitute the main sources of pollution.  Kano is the centre of Nigeria's tanning industry, and is home to 70 percent of the country's tanneries (World Bank, 1995b).  The waste bi-products from these tanneries have high concentrations of the heavy metals chromium and cadmium, and a 1989 study, which monitored the activities of 15 tanneries in Kano, found that in all cases permissible limits for effluent discharge were violated, with the exception of pH and temperature (World Bank, 1995b).  Osae-Addo (1992) adds that not only do down-stream fish and crops become heavily contaminated by heavy metals, but human health is further threatened in urban and peri-urban Kano, because over 60 percent of local people depend on rivers and groundwater aquifers in the area for water.

Methodology
In the field research on which this paper is based, three agricultural sites (Kwarin-Dankukuru, Jakara and Kofar Ruwa) were selected in urban and peri-urban Kano and water samples were taken at various points from the Getsi Stream and Jakara River. An attempt was made to examine water quality both temporally and spatially, and sample sites were selected on a transect, moving away from the city centre into the peri-urban zone.  The Kofar Ruwa site and Jakara site off Airport Road were chosen because they are situated close to the centre in areas of high population density, while the Kwarin-Dankukuru site, which is located at the urban periphery, serves as a good comparison of how water quality varies spatially over the urban and peri-urban zones (see Figure 1).  At Kwarin-Dankukuru, water was sampled from both an irrigation channel and a washbore (6-8 metres deep), so that comparisons could be made between the two sources. Water samples were also taken from the Getsi Stream in the nearby Bompai Industrial Estate, since this is the main source of industrial pollution at Kwarin-Dankukuru.

Insert figure 1 about here

Within the three agricultural sites, five sample locations were selected, and three main catagories of (waste) water were identified:
1.	Industrial wastewater was found at the sample sites at Getsi Stream (within the Bompai industrial estate) and the irrigation channel at Kwarin-Dankukuru.
2.	Domestic wastewater was identified at the sites at Kofar Ruwa and within the Jakara Channel (near Airport Road bridge).
3.	Ground water, was sampled from a washbore at Kwarin-Dankukuru irrigation site.

Following preliminary discussions and on-site transect walks with local farmers at all three sites, it became apparent that almost all channel irrigation was carried out during the long dry season, roughly between the months of September and May.  During the 'wet' months of June, July and August, farmers rely on rain-fed irrigation, and due to the high cost of petrol and diesel fuel, they will only use their motor-driven pumps in situations when it is abnormally dry during this period. As such, the majority of sampling for the study was carried out during the month of April, at the end of the long dry season, since this was the critical period when farmers were irrigating on a daily basis and there were no natural water flows to dilute toxins in the channels. However, a set of samples was also taken during August, the wettest month, in order to compare between water quality in the wet and dry seasons.  

During the month of April, samples were collected on the same day of the week for three consecutive weeks.  Water specimens were taken both in the early morning and in the afternoon, as it was noted that local factories release pollutants into water courses at different times during the day, causing daily temporal variations in water quality.  Laboratory analysis was undertaken by the Central Laboratories at Bayero University, Kano and, in addition to pH and electrical conductivity, standard spectrophotometric procedures were followed for the analyses of cobalt (Co), iron (Fe), nickel (Ni), manganese (Mn), copper (Cu), sodium (Na), potassium (K), lead (Pb), chromium (Cr), mercury (Hg) and cadmium (Cd).  Titrometric methods were used to analyse magnesium (Mg) and calcium (Ca).  Although a wide range of parameters could have been potentially selected for analysis, the choice of elements tested was limited to some of those trace elements which are typically associated with discharges from tanneries and textile mills - two of the major polluters in the Kano industrial estates.  Previous studies in the Bompai and Sharada industrial estates have already indicated that water contamination from heavy metals, such as lead, mercury, chromium, and cadmium is rife, (see for example, Tanko 2002; Ahmed and Tanko, 2000; Tanko, 1997a).  However, it should be noted that this study did not examine levels of pathogens associated with faecal contamination, but it is already generally accepted that sewage wastewater pollution is a significant problem in Kano (Tanko, 1997b).  Previous research from other countries, such as the study by Shuval et al. (1986), reveals that exposure to raw sewage wastewater significantly increases the risk of contracting cholera, as well as infection by Ancylostoma (hookworm) and Ascaris (nematode).  

An irregular level of pH, the measure of acidity or basicity of water, is rarely a problem in itself, but normal levels of samples should be between 6.5 and 8.9, and values outside this range indicate that there are severe abnormalities in water quality (Pescod, 1992).  Electrical conductivity, another standard measurement in irrigation water assessment, is used to determine the ionized constituents of water, which is generally closely correlated with total salt concentration. Plant growth, crop yield and the quality of produce are all affected by the salinity of the soil, which is often determined by the salt concentration of irrigation water.  The optimum EC level for irrigation water is 2 millimho/cm, whilst values which exceed this level will reduce the water osmotic potential, or the rate of water entry into the crops (Tanko, 2002).  For this study, the selected elements cobalt, copper, iron, manganese, nickel, lead, chromium, mercury, cadmium, magnesium, and calcium were tested, and Table 1 below indicates the phytotoxic threshold levels of these elements for crop production.  Abnormal levels of these elements will lower the nutritional nature of the irrigation water and may have inhibitory effects on plant growth.

Table 1: Phytotoxic threshold levels of
Selected trace elements for crop production

Element	Recommended maximum	
	concentration in mg/l	
Co (cobalt)	0.05		
Cu (copper)	0.2		
Fe (iron)	5		
Mn (manganese)	0.2		
Ni (nickel)	0.2		
Hg (mercury)	n/a		
Cr (chromium)	0.10		
Cd (cadmium)	0.01		
Pb (lead)	5.0		
                                                     Source: Pescod, 1992: 17

The results of the analysis are summarised in Table 2 and are discussed under the appropriate site sub-heading according to site location.  In addition to the quantitative data collected, extensive interviews were conducted with producers at each site, and their concerns about water quality further suggest that there is an urgent need to ameliorate the considerable health and environmental hazards associated with agriculture in urban and peri-urban Kano.

The Kwarin-Dankukuru Site
Contaminated irrigation water originating from the Bompai industrial estate is used extensively in many parts of peri-urban Kano, particularly at the agriculture site at Kwarin-Dankukuru.  This site, located furthest from the urban centre, exhibits the most 'rural' characteristics of the sites examined in this paper.  Whilst Kwarin-Dankukuru does not display the mosaic of different land uses that the others do, and is primarily defined by agricultural use, the effects of industrial wastewater do extend to this area, as is reflected in the results of the water samples analysed.  At this site, irrigation water was sampled at the confluence of the Jakara River (which carries mainly residential effluents) and the Getsi Stream, and high levels of toxins were revealed in the analysis. Sampling was also carried out slightly upstream from this site in the Getsi portion of the water system (Figure 1) within the Bompai industrial estate, which seems to be the main source of pollution at Kwarin-Dankukuru. Farmers commented that a number of years ago, even in the dry season, there used to be large volumes of water from residential areas flowing through the Jakara, which would dilute the industrial pollution in the Getsi.  More recently, however, increased water scarcity in Kano has forced residents to use less water domestically, and consequently, there is less residential runoff.  However, this does not appear to dissuade local growers from using the water and many farmers continue to irrigate even though toxicity levels are now much higher.  One morning, a farmer remarked that he could see that the water quality was not very good at that moment, and his vegetables might get 'sick' if he irrigated.  However, he admitted that he had no choice but to use the water, because if he did not, his vegetables would certainly die.

Wastewater from the Bompai industrial estate is released, without any form of treatment, into the Getsi Stream. A significant proportion of the factories in operation at the industrial estate are tanneries and textile mills, and samples of water show high levels of contamination from their discharges (see Table 2).  Pollutants such as mercury, chromium, lead and cadmium were found to be in excess of the recommended permissible levels for releases both by industries (Federal Environmental Protection Agency, 1990) and also for irrigation (FAO, 1976).  While research undertaken in Kano's second industrial estate at Sharada shows similar characteristics (Tanko, 2002), another study has established that the pollutants have begun to affect the quality of water in shallow hand-dug wells around the Bompai residential areas (Tanko, 1997b).

Field observations during this study also revealed that PVC pipes used underground for supplies of domestic potable water in the settlements surrounding Bompai, pass across the Getsi Stream.  Breakages in these pipes provide inlets for chemical contamination, especially when the water pressure within the pipes is low.  In this respect, local residents face a serious risk of ingesting heavy metals associated with industry, through contaminated drinking water. Gradual accumulation of these toxins is quite obviously a serious threat and can lead to severe health problems (see Nash, 1993).  Whilst some contaminants were found to be present in water sampled from a washbore at Kwarin-Dankukuru, the water was free of heavy metals (see Table 2).  Although previous research has revealed traces of these metals in shallow hand-dug wells around the Bompai settlement, (Tanko, 1997b), no evidence of such contamination was found in the current study, suggesting that deep ground water sources may be a good alternative to farmers in urban and peri-urban Kano, for the irrigation of their crops.

Table 2: Concentrations of chemical pollutants at three peri-urban agriculture sites in Kano

S/No.	Date	Time 	Site	PH	EC 	Co	Fe	Ni	Mn	Cu	Na	K	Hg	Cr	Cd	Pb	Mg	Ca	
1	09/04/02	7:30am	Kwarin Dankukuru (irrigation)	7.5	0.47	0	38.5	0	3	0.7	35.6	15.1	17.4	46.7	27.2	39	27	21.4	
2	09/04/02	6:00pm	Kwarin Dankukuru (irrigation)	8.2	0.52	2.5	35.4	271.7	8.6	0.7	20.3	8.5	14.3	36.3	20.1	31.2	18.6	19.8	
3	09/04/02	7:45am	Kwarin Dankukuru (washbore)	5.6	0.09	19	17.7	75.3	0.7	0.5	10.2	2.8	0	0	0	0	15.6	23.1	
4	09/04/02	6:15pm	Kwarin Dankukuru (washbore)	6.2	0.09	5.8	27.7	115	0	2.1	20.3	30.2	0	0	0	0	13.5	22.5	
5	09/04/02	8:30am	Getsi Stream (within Bompai)	8.6	1.28	1.4	1	0	2.6	2.6	61	12.3	18.6	48	28.5	40	18.5	16.4	
6	09/04/02	5:30pm	Getsi Stream (within Bompai)	9.5	1.38	5.8	34.6	0	2.5	2.1	190.7	119.8	15.5	40.1	21.5	34	16.7	15.4	
7	09/04/02	9:30am	Kofar Ruwa (irrigation)	6.6	0.16	17	42.3	45	3	3.1	28	9.4	0	0	0	0	6.3	8.8	
8	09/04/02	4:45pm	Kofar Ruwa (irrigation)	6.9	0.18	4	28.5	60	3.7	2.8	105.9	231.1	0	0	0	0	4.5	7.2	
9	09/04/02	9:00am	Jakara Channel (Airport Rd.)	7.1	0.46	2.6	15.4	75	0.5	1.1	22	21.7	0.1	0	0	0	5.2	7.4	
10	09/04/02	5:00pm	Jakara Channel (Airport Rd.)	7.5	0.55	7.4	34.6	38.3	0.4	2	30.5	51.7	0.1	0	0	0	3	8.7	
																			
11	16/04/02	7:40am	Kwarin Dankukuru (irrigation)	8.2	0.65	1.1	34.6	63.3	1.4	1.9	96.6	16	18.6	45	28.1	41.2	28.2	20	
12	16/04/02	5:15pm	Kwarin Dankukuru (irrigation)	10	0.76	0.9	33.9	128.3	3	3.2	81.4	14.2	15.3	32.5	21.2	31.8	19.5	14.2	
13	16/04/02	7:55am	Kwarin Dankukuru (washbore)	6.4	0.09	5.8	45.4	115	3.7	2.7	20.3	23.6	0	0	0	0	16.7	18.6	
14	16/04/02	5:45pm	Kwarin Dankukuru (washbore)	7.1	0.09	5.6	43.9	63.3	6.1	2.2	8.5	2.8	0	0	0	0	11.7	15.6	
15	16/04/02	7:15am	Getsi Stream  (within Bompai)	10.5	1.43	4.4	28.5	0	2.1	0.9	61.9	15.1	18	47.5	28.9	46.2	16.2	16.2	
16	16/04/02	4:50pm	Getsi Stream (within Bompai)	10.5	1.28	6.3	21.5	66.7	0	1.6	189.8	201.9	15.5	38	22	37.4	17.7	15.2	
17	16/04/02	8:53am	Kofar Ruwa (irrigation)	7.5	0.16	2.8	17.7	23.3	3	2.6	12.7	9.4	0	0	0	0	7.2	8.4	
18	16/04/02	4:15pm	Kofar Ruwa (irrigation)	7.2	0.19	0.7	36.9	160	3.5	2.5	28.8	109.4	0	0	0	0	5.8	8	
19	16/04/02	8:30am	Jakara Channel (Airport Rd.)	8.3	0.39	3.4	20.3	17.8	2.6	1.7	33.2	20.1	1.6	0	0	0	5.3	11.5	
20	16/04/02	4:35pm	Jakara Channel (Airport Rd.)	7.5	0.43	3.2	29.2	22	3.7	2.7	54.2	26.1	0	0	0	0	4.6	10.6	
																			
21	23/04/02	7:40am	Kwarin Dankukuru (irrigation)	7.9	0.48	4.7	23.6	96.7	7	3	78	250	16.8	48.8	26.2	41.8	27.4	18	
22	23/04/02	5:35pm	Kwarin Dankukuru (irrigation)	8.2	0.75	0	39.2	0	4.4	2.5	106.8	14.2	14.6	36.7	20	36.2	20	17.2	
23	23/04/02	7:50am	Kwarin Dankukuru (washbore)	7.5	0.1	3.9	37.7	75	0	2.1	20.3	3.8	0	0	0	0	12.4	24.5	
24	23/04/02	5:42pm	Kwarin Dankukuru (washbore)	7.7	0.12	8	40	0	3.3	2.1	24.6	2.8	0	0	0	0	16.4	24	
25	23/04/02	7:10am	Getsi Stream (within Bompai)	10.6	0.67	9.8	18.5	190	0.7	1.2	111	7.6	18.6	49	28.6	46.2	18.6	17	
26	23/04/02	6:15pm	Getsi Stream (within Bompai)	8.8	1.43	2.6	30.8	158.3	0	1.9	189.8	11.3	16.4	46	21.8	38.2	17.2	16.3	
27	23/04/02	8:47am	Kofar Ruwa (irrigation channel)	8.1	0.23	2.1	23.9	206.7	2.6	2	37.3	12.3	0	0	0	0	6.2	8.7	
28	23/04/02	4:30pm	Kofar Ruwa (irrigation channel)	8	0.23	9.3	34	153.3	2.8	2.2	36.4	12.3	0	0	0	0	6	8.6	
29	23/04/02	8:25am	Jakara Channel (Airport Rd.)	8.8	0.38	7.9	36.9	118.3	2.8	2.2	51.7	13.2	0	0	0	0	4.8	11.6	
30	23/04/02	4:55pm	Jakara Channel (Airport Rd.)	8.4	0.44	9.3	34.6	118.3	3.5	1.5	56	16	0	0	0	0	5.6	7.6	
																			
31	04/08/02	8:30am	Kwarin Dankukuru (irrigation)	7.5	0.28	20	36.9	86.7	4	2.2	22	4.7	14.4	26	17.2	27.2	18.1	14.3	
32	04/08/02	5:00pm	Kwarin Dankukuru (irrigation)	7.3	0.14	23	33.1	46.7	2.6	1.7	28.8	25.3	10	12	10.8	15	10.2	10.1	
33	04/08/02	8:45am	Kwarin Dankukuru (washbore)	6.5	0.08	0.7	35.4	171.7	8.6	0.7	26.7	13.2	0	0	0	0	17.6	23	
34	04/08/02	4:45pm	Kwarin Dankukuru (washbore)	6.5	0.08	2.1	30.1	160	7.8	2.1	25.3	12.6	0	0	0	0	15	16.3	
35	04/08/02	7:45am	Getsi Stream (within Bompai)	7.15	0.15	0	34.6	55	0.5	2.8	9.3	28.3	14.6	26	18.4	27.4	18.4	17.3	
36	04/08/02	4:30pm	Getsi Stream(within Bompai)	7.45	0.16	5.6	30.5	86.3	2	1.8	110	22.2	9.5	10	10.5	17	10.6	14.6	
37	04/08/02	10:15am	Kofar Ruwa (irrigation)	7.2	0.21	3.5	39.2	140	3.3	3.5	20.3	10.4	0	0	0	0	6.5	8.3	
38	04/08/02	6:30pm	Kofar Ruwa (irrigation)	7.2	0.15	2.8	39.2	165	0.4	1.7	16.1	8.5	0	0	0	0	5.2	5.3	
39	04/08/02	9:45am	Jakara Channel (Airport Rd.)	7.4	0.27	1.1	30.8	81.7	4	1.9	17	15.1	0	0	0	0	7.6	6.8	
40	04/08/02	6:00pm	Jakara Channel (Airport Rd.)	7.3	0.15	2.1	2.5	80.5	3.2	2	17	18.2	0	0	0	0	6.5	6.5	
EC–measured in /s
Co, Fe, Ni, Mn, Cu, Na, K, Hg, Cr, Cd, Pb, Mg, Ca –measured in mg/l

Source: Authors’ survey, 2002

All the farmers interviewed at Kwarin-Dankukuru expressed great concern about the current environmental state of the site. Since the livelihoods of farmers depend on their crop production at the site, both in terms of home consumption and income generated from the sales of produce, it is perhaps no surprise that most cultivators possess a great deal of environmental knowledge, and are well aware of the conditions that constrain them.  For example, farmers can distinguish water toxicity levels by colour and can provide detailed descriptions of the temporal variations in water quality. For example, according to one respondent:

There are three bad colours [of water] that come at different times.  The oily red one 
and the green one will kill the crops, and when we see these colours in the channel,                                  we turn off our pumps immediately.  The bluish water is corrosive and causes a red rash when it comes in contact with the skin. We always wash our hands after we come in contact with the blue water 
(Sadanu, pers. com., 2002).

Another farmer commented that he had recently noticed a very serious increase in the amount of red water being released into the channel.  He explained that the colour had become much more intense, almost to the point where it was now black, and he added:

If you put your hand in this water, it will stain your skin. This water burns the soil, 
and there are patches now that won't yield anything anymore 
(Nuhu, pers. com., 2002).

Many farmers were also able to make a connection between these poor quality waters and the degradation of the soil.  One cultivator pointed out that because of the water quality, the soil on his plot had developed a dark, blotchy stained look on the surface, and the soil texture had become oily.  He demonstrated that when he irrigated his plot, the water would no longer penetrate the soil, but instead floated on the surface and then ran off, causing the crops to 'starve'.  The process being described is referred to by soil scientists as ' deflocculation', and occurs as a result of high levels of sodium salt and a deficiency of calcium and magnesium.  Although the farmers do not understand the chemical process whereby the soil loses its structure, they are keenly aware that using toxic water has exacerbated the situation.  Referring to Table 2, it is apparent that the levels of both calcium and magnesium have shown lower relative values in relation to sodium. The calculated Sodium Adsorption Ratio (SAR) for the water at the irrigation site shows a value of 4.34. Whilst this is an acceptable value for irrigation (FAO, 1976), it clearly shows potential for sodicity development, and therefore concurs with what the farmers indicated.  Perhaps of greater concern, however, is that other pollutants in the effluents, such as the heavy metals lead, mercury, manganese, and cobalt, have specific ion toxicity effects on the crops. This may explain why the plants cannot germinate on many of the plots at the site. Where crops do germinate, there still remains a fear that chemical toxins may be absorbed through plant root systems, and later ingested by humans through the food chain, as described by Ahmed and Tanko (2000). A detailed exploration of the effects of wastewater contaminants on plant samples is beyond the scope of this paper. However, there is clearly a need for further research to explore how crop growth is affected by high concentrations of industrial waste. Furthermore, although contaminated crops are consumed over an extended period and concentrations of toxins accumulate in local communities, the health impact on urban and peri-urban populations is presently unclear. Longitudinal studies are urgently needed to clarify such health issues.

The other main soil problem pointed out by farmers at Kwarin-Dankukuru was that irrigated plots apparently often developed a 'crust' on their surface, and would not allow water or air to infiltrate.  The processes of 'sodicity' and 'salinization' were both apparent, and were probably due to excessive levels of sodium in the water. This condition is easily recognisable, as 'chalky' white salt deposits can be seen on the soil surface. Although salinity problems are usually more severe in arid and semi-arid environments such as Kano, such problems can be intensified by polluted irrigation water.

A final concern that was universally shared by all farmers interviewed at the site involved the seriousness of the polythene bag pollution problem.  At Kwarin-Dankukuru, plastic bags are not only transported to the site among piles of urban waste to be used as fertilizer, known locally as shara, but bags are also deposited on plots through the irrigation channel.  Huge volumes of bags arrive at the site during the rainy season, when water levels are higher and currents can transport debris more readily. Not only do the bags clog drains, but stagnant pools form, encouraging the spread of diseases such as typhoid and malaria.  Although some farmers have tried to dispose of the bags by gathering them together and burning them in large piles, it is reported that it remains very difficult to eliminate their presence completely, and during the dry season they can be seen blowing about on farm plots.

Jakara Site (off Airport Road)
Domestic waste water released from the residential areas of Kano’s ancient walled city, Sabon Gari, and Gwagwarwa all drain into the Jakara channel, which flows into the Jakara River.  Unlike the water in the Getsi, the Jakara water shows no evidence of pollution by heavy metals. While some small-scale tanneries are located in certain parts of the old city, field visits confirm that no metals are used in the tanning process.  However, referring to Table 2, it can be seen that other pollutants, including cobalt, manganese, and iron, have been found in high concentrations. These may pose toxicity problems to crops, since most crops lack the complex, internally balanced homeostatic mechanisms that regulate body function and adaptation that are found in animals.

Substantial vegetable production takes place using the polluted water near the Airport Road bridge and crops are irrigated by water from the Jakara channel.  Farmers report observing colour differences in effluents at different times during the day, indicating that there are also temporal variations in water quality in the Jakara. This observation is reflected in the values of the tested parameters, taken in the morning hours and afternoon hours (see Table 2).  As Figure 1 shows, the Jakara joins the Getsi, and thus the water in the Jakara helps to dilute toxins originating from the tanneries and textile mills in the downstream portion of the Getsi system. 

The Jakara site is located near Airport Road bridge in a high-density residential area.  Substantial vegetable production takes place on the south west side of the road, and crops are irrigated by water from the Jakara channel, which flows through the Birni (old city), Fagge, Sabon Gari, and Gwagwarwa, and serves as the main drain for built-up areas along the way.  Since most of the water entering the irrigation channel comes from residential sources, this helps to dilute toxins originating from the tanneries and textile mills, but pathogenic viruses, bacteria, protozoa and helminths are often present in municipal wastewater, and are an additional health hazard to local people (Pescod, 1992:33).  Alternatively, of course, liquid waste from sewage can be a valuable commodity in UPA, and contains many useful elements such as nitrogen, potassium and phosphorus.  As Pescod (1992) suggests, if local authorities were able to harness the beneficial characteristics of domestic wastewater, surface water pollution problems would not only be mitigated, but valuable water resources would be conserved and dependence on commercial fertilizers might be lessened.  

Kofar Ruwa Site
The Kofar Ruwa production site is located in a low-lying fadama depression adjacent to the north-eastern part of the old city wall.  The site is situated in the floodplain of a small tributary of the Jakara River, which serves as a drain for urban wastewater in the built-up area immediately to the north of the city wall.  The construction of a sewage treatment scheme was initially started in the late 1960s to treat waste water from the Gwammaja housing estate and Dala Orthopaedic Hospital, but the project has long been abandoned.  Like other UPA sites in and around Kano, sources that supply irrigation water are heavily polluted and have been flagged as a major environmental and health concern.   

Previous interviews at the Kofar Ruwa site, conducted by the authors over a four-year period, reveal that perhaps the major constraint faced by farmers in the area is that of insecurity of tenure (Lynch et al., 2001).  However, more recent interviews conducted for the present study suggest that concern about the quality of available water was also a significant issue for many farmers.  According to one cultivator, both the odour and colour of water sources change periodically at Kofar Ruwa, especially during the dry season, and sometimes the poor quality of irrigation water will 'burn' the lettuce and cause it to 'dry up'.  As Table 2 indicates, although no traces of heavy metals were detected in the samples taken at the Kofar Ruwa site, toxicities of some of the domestic contaminants, especially manganese, were detected and this can cause the 'drying up' of crops.  Also of great concern are the high salinity and sodicity indices.  Sodium has a mean value of 38.5mg/l, and the water has a calculated Sodium Adsorption Ratio (SAR) of 16.8, which is high enough to cause loss of soil structure and deflocculation.

In addition to concerns about water quality, a number of respondents at Kofar Ruwa admitted that the general lack of water in the dry season was also a problem, and sometimes farmers were forced to use poor quality water on their plots.  Prolonged use of this polluted water caused the soil to 'die', according to one farmer.  In the past, admitted a second farmer, the authorities have warned the public not to consume vegetables which are grown at Kofar Ruwa, especially at times when cholera was a threat.

Conclusion 
Of the many environmental concerns that need to be urgently addressed in urban and peri-urban Kano, increased levels of pollution in local water sources are at the top of the agenda and deserve immediate attention.  According to one World Bank report, advisors warn that water contamination has the second highest potential for future negative impacts on GDP, and in Nigeria alone, higher incidences of water-related diseases cost the country an estimated US $1 billion annually through increased health costs and lost productivity, and put 40 million people at risk (World Bank, 1990).  In greater Kano, water treatment and even water supply facilities are virtually non-existent, such that poor people, including those who engage in urban farming practices in order to try and make ends meet, cannot afford defensive sanitary practices.  Local surface water is of vital importance, and the shallow ground water supplies found in fadama depressions where much of the peri-urban agriculture takes place, are highly polluted with urban and industrial contaminants.

At Kano's three industrial estates – Bompai, Challawa, and Sharada – industrial sludge and liquid waste are routinely deposited in open drains, sewer systems and water courses without treatment.  The waste treatment facilities that do exist are either inadequate or not functioning, and very little enforcement takes place.  Poor zoning and enforcement by-laws in the industrial areas seem to exacerbate problems, as landowners continue to sell their property to housing developers, since few new manufacturing facilities are being established in Kano at the present time.  As long as such practices continue, housing encroachment and urban agriculture will continue alongside industry, pollution rates will continue to rise at an alarming rate, and the health of the local population will remain in jeopardy.

It should also be noted that in Kano, and indeed other Nigerian cities, penalties for violating industrial standards are very lax, or in some cases non-existent.  Market-based incentives to reduce pollution, such as the 'polluter pays' principle, or grants, subsidies and tax credits for environmentally friendly behaviour, either do not exist or are ineffective.  Further compounding these problems, responsibility for pollution control enforcement is not clearly defined, and both state and federal governments seem to disagree on who should be liable.  Co-ordination among environmental agencies is weak and a new concerted programme of action is urgently needed to stimulate effective strategies for management of the urban and peri-urban environment.  

The field research for this study has raised some important health and environmental concerns associated with UPA in and around Kano.  Whilst the focus of the enquiry has been on just one city, in reality the findings are by no means situation specific, but may have much wider relevance for other large cities in Africa.  It seems that a number of key issues require urgent attention in Africa’s rapidly growing cities;

•	The scarcity and prohibitive cost of irrigation water and chemical fertilizer have forced many local actors to seek unsustainable alternatives which are currently jeopardizing both health and environment in urban and peri-urban areas. Improving access to safer resources should be a top priority.

•	Industrial pollution management capabilities are severely constrained at institutional levels, both financially and technically, and there is a lack of effective implementation of environmental management laws. Substantial investment and community action are needed in urban and peri-urban waste management.

•	There are many linkages between environment, health and UPA, such that a holistic understanding is urgently needed. In order for improved management techniques to be implemented, a condition that is crucial for food security, environmental and health impact assessments must be conducted in order to identify these linkages and to evaluate the relative seriousness of different situations.  Only after such assessments can sustainable solutions be proposed and then implemented.

•	Levels of pollution in urban and peri-urban water sources vary both temporally and spatially, and there may be safer times and locations where agriculture can be encouraged by authorities.  There is an urgent need, therefore, for UPA practices to be carefully monitored both spatially and temporally. 

The benefits of UPA are far-reaching, in terms of providing employment, food security and income generation, and these have been well documented in the literature.  It is evident that the food production sites examined in this study provide a valuable resource for meeting the challenges of a rapidly growing city, and many Kano residents now rely heavily on food grown on urban and peri-urban plots in order to make ends meet.  However, at the same time as the competition for scarce resources continues in and around Kano, it seems that financially strained governments, at municipal, state and federal levels, can no longer manage the environment effectively.  Indeed, there is much cause for concern, and the resolution of many problems concerned with environment and development in urban and peri-urban areas, will undoubtedly be determined by the quality of governance at various levels, a key issue identified in the recently published ‘World Water Development Report’ (UNESCO, 2003).  

Despite a considerable body of literature that has examined urban health issues, there have been relatively few studies that have explored the environmental and health aspects of UPA, and there is a pressing need for further research in this context.  In particular, comparative longitudinal studies are needed to evaluate the different short-, medium- and long-term impacts of pollutants on crops and human well being.  As African cities continue to expand at alarming rates, the proliferation of UPA seems likely to continue unabated, and it is essential that such activities become both safer and more sustainable.  
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Acknowledgements
The authors would like to acknowledge the valuable assistance of Mr Garba Kofar Naisa Adamu of the Geography Department, and the staff of the Central Laboratories, at Bayero University, Kano, in analysing the water samples.

Figures
Figure 1 (Map) Kano: location of survey sites.

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